<style type="text/css">
    .test
    {
        font-size: 1em;
    }
    .test:before
    {
        content: "\007B\002A[";
        font-size: 2em;
    }
    .test:after
    {
        content: "]\002A\007D";
        font-size: 2em;
    }
</style>

<span class="test">Hello</span>